When cooling electronic or other systems, for which temperature regulation is required, it is often necessary to employ multiple cooling devices (fans, blowers, etc. . . . ). In the event that one or more of the cooling devices fail, there is often a need to prevent the recirculation of cooling air between active the remaining operational devices and those (1 or more—most often only 1, which will be replaced with routine maintenance) which have failed. To illustrate this please refer to prior art FIG. 1, in which a standard prior art ventilation flow is shown. The desired rotation of the fan rotor I indicated by the number “1” and the associated desired airflows are indicated by the green arrows. When the fan fails the rotor will rotate in the opposite direction, indicated by the number “2” and the associated undesirable airflows are indicated by the arrows. The entire recirculation (or back flow) loop is now established. The majority of the related prior art solutions employ devices such as louvers (indexed as “L”) or vanes to relieve the recirculation issue.
Prior art FIG. 2 illustrates a “vanes” or “louvers” thermal solution. In this prior art solution, when the fan is operation under normal conditions, there are louvers (or vanes) that rotate to a position that I perpendicular to the desired airflow and on “fan failure” the louvers/vanes fall to cover the face of the fan that would be on the downstream side of the airflow, when under normal operating conditions.
One of the problems with the vanes or louvers is that they require space that is downstream of the fan, noted as FP(2) or “footprint” and that this space is wasted. In addition, vanes often become an issue from the perspective of acoustic noise, due to vibration of the vanes when floating in the airflow from the cooling devices.